A uniflow-scavenged two-cycle engine that is also used as an engine in a ship is provided with a scavenging port in one end portion side and an exhaust port on the other end portion side of a piston in a stroke direction in a cylinder. When active gas is suctioned from the scavenging port to a combustion chamber in an intake (feeding) stroke, exhaust gas produced in combustion behavior is pushed and is exhausted from the exhaust port with the suctioned active gas.
For example, Patent Document 1 discloses an engine that includes a cylinder to which a fuel injecting valve is attached and fuel gas is supplied into the cylinder from the fuel injecting valve. In addition, a configuration, in which the cylinder is provided with the fuel injecting valve on an outer side thereof and the fuel gas is provided into the cylinder from a scavenging port, is considered. When the fuel injecting valve is opened and the fuel gas is supplied into the cylinder, the fuel gas and active gas are compressed through a compression stroke and the fuel gas ignites and combusts in the combustion chamber. A piston reciprocates in the cylinder due to explosion pressure produced by an effect of the combustion.